Wells that produce gas and have concurrent production of liquids such as water, oil or condensates, are often incapable of clearing these liquids from the well bore. This is especially true in depleted reservoirs and low-rate gas wells. Liquids accumulate in the well bore as gas is produced. Accumulated liquid exerts backpressure on the producing formation such that flow of gas is reduced or completely restricted.
Existing technology for dewatering of gas wells can be divided into two general categories: high cost and low cost. For the purposes of this specification the term dewatering encompasses the removal of liquids including but not limited to water.
Typical high cost dewatering methods for reducing liquid accumulation in the well bore and reestablishing a viable gas production rate usually involve external energy sources to power a pumping technology such as down-hole pumps. One problem with external energy sources such as down-hole pumps is that many pumping methods are labor intensive, require regular attention and generally use expensive equipment to provide an external source of lifting capacity to clear the well bore of the liquids. As a result, these technologies are cost prohibitive, and are often not economically viable for low production wells.
Low cost dewatering technologies have a narrow operating range, and must be suited to each individual well based on well characteristics such as water gas ratio (WGR), well pressure, and gas flow rate. This information is often unavailable, and can be highly variable over time. Low cost technologies generally require regular attention from operations staff which can be problematic in areas of limited or restricted lease access. The narrow operating range of low cost dewatering technologies means that they usually fail when well conditions change in such a way that they are outside of the operating range. Failure of these technologies results in down time and lost production, and can also require attention from operations staff in order to resume production.
A need therefore exists for a well dewatering method and system that overcomes at least one of the above mentioned shortcomings associated with existing technologies or at least overcomes one shortcoming inherent to existing and potential well dewatering systems further to those described above.